The MAIN GOAL of this project is to understand the mechanisms regulating cellular growth of human fetal and adult prostate with the emphasis on the role of mesenchyme-epithelial interactions and growth factors (KGF, TGFalpha, and TGFbeta). The RATIONALE for this proposal is that the developing prostate is an appropriate paradigm for mechanistic studies of growth regulation by paracrine mechanisms in normal and hyperplastic prostates. This project is based on the HYPOTHESIS that the endocrine and developmental control of prostatic cell growth may be regulated by cell-cell interactions mediated by the local production and action of peptide growth factors. In order to test this hypothesis that paracrine mechanisms may be involved in growth and differentiation of developing and adult prostate, we will pursue the following SPECIFIC AIMS: 1) To elucidate the paracrine mechanisms in the regulation of human prostatic growth and differentiation. This will be achieved by grafting human fetal prostates into male athymic nude mice. The resultant growing human fetal prostatic tissue will be examined for a) growth kinetics (doubling time and 3H-thymidine labeling index), ductal elongation and branching morphogenesis, and expression of differentiation markers (PSA, PSAP) by immunohistochemistry and western blot; b) expression of KGF, TGFalpha, and TGFbeta and their receptors by RT-PCR, nuclease protection assay, northern blot, and immunohistochemistry; c) the effects of exogenous KGF, TGFalpha, and TGFbeta and their neutralizing antibodies on organ cultures of growing human fetal vs. adult human prostate (BPH) tissue; d) regulation of KGF, TGFalpha, TBFbeta levels by androgens; e) determination of temporal and spatial aspects of growth factors and their receptors in fetal and BPH tissue. 2) To determine the growth promoting and morphogenetic effects of human urogenital sinus mesenchyme (UGM) on growth-quiescent adult human prostatic epithelium. For this purpose we will isolate UGM and combine it with human prostatic epithelial cells. The resultant tissue recombinant will be grown in athymic nude mice and will be characterized for growth and development as described under Specific Aim #1. 3) To investigate the role of growth factors and cell- cell interactions in the prostate using a new BPH-derived epithelial cell line. This specific aim will be achieved by determining KGF, TGFalpha, and TGFbeta as regulators of prostatic epithelial growth and development. We will also examine the role of prostatic epithelium in the induction of smooth muscle differentiation. Accomplishment of these objectives will elucidate the mechanisms regulating prostatic growth and development by mesenchymal epithelial interaction mediated by the local production and action of growth factors. Through this multidisciplinary approach, we will definitely establish the role of these growth factors as paracrine/autocrine growth regulators in the human prostatic development. The LONG-TERM OBJECTIVES of the proposal are to develop the best strategy for regulation of prostatic growth.